Ensuring safe, reliable drinking water each time Sydney’s ever-growing population turns on a tap is a significant and evolving challenge. SUEZ’s Prospect Water Filtration Plant is on the frontline in meeting this essential need.
The Prospect Water Filtration Plant in Sydney’s west is one of the largest potable water contact filtration facilities in the world. For more than two decades it has supplied safe and reliable drinking water to up to 85 per cent of the population, or enough for about four million people.
The plant was built between 1993 and 1996 on a Build, Own and Operate Public Private Partnership model with Sydney Water, combining SUEZ’s international water management expertise and the local project management and construction experience of project partners Civil & Civic (Lend Lease), and commenced operation in 1996.
Located on the edge of the Prospect Reservoir in Wetherill Park, the plant is fed from three raw water sources. The primary source is Lake Burragorang, with water extracted at Warragamba Dam, supplying the plant via two 30km pipelines. The Upper Canal is the secondary source, collecting and transporting water from the Upper Nepean System 64km to the plant via gravity, with Prospect Reservoir – the third water source, accessed using a dedicated pumping station.
The plant is unique for several reasons, including its low energy consumption, small footprint, innovative processes, high water efficiency and proven reliability over more than 20 years of operation. Fed by gravity, the plant’s loss of head is less than 5.5m, allowing for an exceptionally low energy consumption of less than 30 watts per cubic metre – equating to less than one hour of lighting per kilolitre of water produced.
The single stage process filtration technology selected for the plant offers high filtration velocity while contributing to a very low footprint, allowing construction of the 3,000MLD (million litres per day) plant – with expandable capacity to 4,200MLD – in a space less than the surface of eight cricket grounds.
The plant treatment line is based on contact filtration, involving coagulation and direct filtration, and SUEZ’s innovative Aquazur® V filtration degremont® technology – a concrete filter using a monomedia filter bed – is at its heart. The filter was adapted to the scale and unique challenges of the plant, using a deep bed of 2.15m with large sand particles of 1.8mm effective size. Twenty-four Aquazur® V filters with a unitary surface of 238m2 deliver a total filtration surface of 5,710m2.
The filters utilise a highly effective backwash system based on air and water followed by water rinsing. This allows excellent cleaning efficiency, a reduction in mud-ball formation, and ensures the superior level of performance so critical at high filtration velocity. Each filter is equipped with its own online turbidimeter, allowing monitoring to take place throughout all stages of the filtration cycle.
The filtration aims to achieve turbidity levels of less than 0.10NTU (nephelometric turbidity units); well below the Australian Drinking Water Guidelines.
In its first 20 years of operation, the Prospect Water Filtration Plant has demonstrated consistent availability, largely reliant on optimised contact filtration and the proven Aquazur® V filter technology.
From an efficiency viewpoint, the plant’s process is extremely well optimised. Backwash from the filters is collected, clarified through settling and filtration and then recirculated to the inlet of the plant, delivering plant’s water loss of less than 0.1 per cent. This exceptional outcome is a result of the use of clarification and filtration in the treatment of the backwash water, allowing recycling of the filtered supernatant with a lower turbidity than the raw water feeding the plant.
The filtration process is completed by a fluoridation step using sodium silica fluoride, and pH correction using lime water. Disinfection is conducted with chlorine gas dissolved in a stream of service water and added to the filtered water upstream of two large clear water tanks.
The contact time provided by the tanks is critical to achieving the disinfection target before ammonia is injected to form chloramines. The potable water then leaves the plant, entering Sydney Water’s network by gravity.
Two decades of highly successful operation has seen the recent extension of SUEZ’s operation contract with Sydney Water for the plant until 2035. Maintaining optimal operations and continuous improvement, the Prospect Water Filtration Plant is well equipped to keep delivering top-quality drinking water for Sydney’s growing population well into the future.
This partner content is brought to you by SUEZ. For more information, visit www.suez.com.au.